1. Technical Field
The present invention relates in general to user interfaces for computers. More specifically, the present invention relates to scroll bars in graphical user interfaces.
2. Background Art
The development of the EDVAC computer system of 1948 is often cited as the beginning of the computer era. Since that time, computer systems have evolved into extremely sophisticated devices that may be found in many different settings. Computer systems typically include a combination of hardware (e.g., semiconductors, circuit boards, etc.) and software (e.g., computer programs). As advances in semiconductor processing and computer architecture push the performance of the computer hardware higher, more sophisticated computer software has evolved to take advantage of the higher performance of the hardware, resulting in computer systems today that are much more powerful that just a few years ago.
Early computer systems required an extensive knowledge of commands for a user to perform any type of function. These computer employed what is known as a command line in which a specific command would have to be entered to perform just about any type of operation. This limited the use of computers to those who had the time to learn a large number of relatively cryptic commands.
Later computer systems used a more advanced user interface to make it easier for a computer user to perform functions without knowledge of specific commands. The most common modern interface is the graphical user interface, or GUI. A GUI uses some type of symbol, menu or other mechanism which is activated by a computer user with a pointing device (e.g., a mouse, a trackball) to perform many commonly performed tasks. These graphical mechanisms are usually designed to be somewhat consistent and self-explanatory to make it as easy as possible for a user to perform common functions.
Most graphical interfaces display documents in a portion of the screen called a window. Where the document is large, only a partial view of the document is visible in the window at a time. To view other portions of a document a graphical device called a scroll bar is used. Scroll bars allow a user to move down or across a document using a pointing device. In particular, the scroll bar allows a user to move to other document portions by either clicking and dragging the slider in the scroll bar or by clicking somewhere on the scroll bar.
Turning to FIG. 8, an exemplary graphical user interface 700 is illustrated. The graphical interface 700 is like many of the current applications and operating systems available that use graphical elements to facilitate commonly used operations. The graphical interface 700, in this case for a word processing program, uses a scroll bar 702 with a slider 704 to facilitate a user moving to view different document portions. With the slider 704 at the top of the scroll bar area 706, the user interface displays the top portion of the document. When the slider 704 is moved to the bottom of the scroll bar area 706, the user interface displays the bottom portion of the document. In the illustrated example, a user can move down in the document by clicking and dragging the slider 704 with a pointing device. Alternatively, the user can move down in the document by clicking on the exposed scroll bar area 706 under the slider 704, or by clicking on the down arrow 708.
Turning to FIG. 9, the graphical user interface 700 is shown displaying a larger document with the slider 704 correspondingly smaller and the exposed scroll bar area 706 correspondingly larger.
Slider sensitivity is a function of the document size and the available scroll bar area. The larger the document, the larger the amount of document movement results from a given amount of slider movement. Thus, with a large document, moving the slider even a small amount results in large amounts of movement in the document. This high sensitivity to slider movement makes it very difficult to scroll by clicking and dragging the slider without "jumps" in the view of the document. Because the desired location in the document may be skipped during a jump, these jumps make it very difficult to controllably scroll the document. Thus, with prior art systems it can be very difficult to effectively scroll though large documents.
Without an improved mechanism for controlling a slider in a scroll bar, the efficient and effective work on large documents will continue to be hampered by the limits of the present day graphical user interface.